1. Field of the Invention
This invention relates to a loading apparatus for a disc-shaped recording medium in which a disc tray supporting the disc-shaped recording medium or record disc is moved between an external disc exchanging position for exchanging the recording medium and an internal playing position for reproduction of information recorded on the medium. More particularly, this invention relates to a loading apparatus having a vibration suppressing unit for suppressing vibrations of the disc tray when the disc tray is in the internal playing position.
2. Description of the Prior Art
An apparatus for recording on and/or reproducing from a disc shaped recording medium, such as an optical disc or a magneto-optical disc with the aid of an optical pickup system is known. Such a disc recording and/or reproducing apparatus is disclosed in the Japanese Utility Model Publication No. 19955/1988 and Japanese patent Publication No. 48162/1986. With this known apparatus, the disc rests on a rotatable disc table which is, in turn, mounted on a supporting base member. An optical pickup adapted to be moved between the inner periphery and the outer periphery of the record disc is also provided on the supporting base member. The supporting base member is, in turn, provided within an outer casing. With this apparatus, the optical pickup unit and the axis of rotation of the disc table are fixed relative to the supporting base member.
This type of disc recording and/or reproducing apparatus is provided with a loading apparatus, the loading apparatus being provided, in turn, with a disc tray adapted for transporting the disc between an external position outside of the casing and an internal position registering with the disc table. That is, the disc tray of the loading apparatus, on which rests the disc, is adapted to be moved between the position in which the disc tray protrudes from the casing and the position in which the disc tray is generally inside the casing and placed on the disc table. The disc tray is also provided with a disc lifting unit. This lifting unit lowers the disc relative to the disc tray along the axis of the disc table to prevent the disc from abutting against the disc table or the optical pickup unit during disc transport and to cause the disc to be placed on the disc table when the disc is positioned over the disc table. Thus, the disc lifting unit has a disc rest movably supported along the axis of the disc table by the disc tray. The disc lifting unit is adapted to be moved by an actuating unit including a cam plate or like member.
The disc recording and/or reproducing apparatus is provided with a disc clamping unit supported so that it is vertically movable on top of the disc table. This disc clamping unit is so constructed and arranged that, when the disc is placed on the disc table, the clamping unit is moved towards the disc table to clamp the disc in cooperation with the disc table.
To load the disc in the player section with the aid of the above described disc loading apparatus, the disc tray is moved to the outside of the casing and the disc is placed on the disc rest of the disc tray. The disc tray is then moved into the inside of the casing. At this time, the disc is moved above the disc table while it is supported on the disc rest. When the disc tray is moved to the position where the center of the disc lies on the axis of the disc table, the disc rest is moved towards the disc table so that the disc is placed on the disc table. The disc clamping unit is then moved towards the disc table for clamping the disc between the clamping unit and the disc table. The information signals may then be recorded or reproduced in this state on or from the disc by means of the optical pickup unit.
With a disc recording and/or reproducing apparatus, having the above described loading apparatus, the disc tray, the disc rest of the disc lifting unit and the disc clamping unit are positioned in the recording and/or reproducing mode by, for example, abutment against associated positioning elements. The disc tray, disc rest and disc clamping unit are simply positioned and held by separate locking pawls or like elements without being secured mechanically. For this reason, the disc tray, the disc rest or the disc clamping unit may be excited into resonant vibrations in resonance due to extraneous vibrations or movements of the objective lens in the optical pickup unit as a result of the focusing or tracking servo control operations.
When the components of the disc recording and/or reproducing apparatus are excited in this manner into vibrational movements, these movements may be propagated to the optical pickup unit or the disc, making it difficult to perform satisfactory focusing or tracking servo control operations. As a result, more powerful servo operations are necessary, which in turn increases the driving current required for the servo operation and causes fluctuations in the driving currents. With the increased intensity of or fluctuations in the driving current, the power supply unit provided in the disc recording and/or reproducing apparatus for furnishing the driving current is rendered electrically unstable.
The power supply unit also furnishes the current necessary for processing the information signals read from the disc or recorded thereon by means of the optical pickup unit. Therefore, when the power supply unit is in an unstable state, information signals cannot be recorded or reproduced satisfactorily.